How to call an unix shell script using a PL SQL stored procedure

I have a an ASP application where I need to upload a CSV file to unix server and then call the stored procedure which will inturn call the shell script to update/insert the csv sheet data to a table. I am not sure how to call a unix sript from the PLSQL procedure.

Why do you want your stored proc to call back a script?...
You can (via UTL_FILE package) load the data from the file within your PLSQL, or even use the fiel as an external table to run a select on and copy data straight into a DBTable...
I would recommend you this approach, if only for security...
Jerome